1. Field of the Invention
The invention relates to an articulated vehicle, more particularly, but not exclusively to a very long railway car for transporting automobiles.
If railway vehicles are to meet the load limit gauge imposed upon them when they travel around curves, the distance between the end axles of a car must be limited, which for a given total loading area in a train multiplies the number of cars required.
The space needed for coupling and for the traction and buffing means for independent cars notably reduces the total loading area of the train.
2. Description of the Prior Art
In order to overcome this disadvantage, articulated railway vehicles comprising two half-frames have appeared; each half-frame is comparable in length to the frame of one independent railway vehicle, and is provided with its own rolling devices at the far ends, while at its other end, each half-frame is supported directly or indirectly on an intermediate underframe provided with rolling devices shared by both half-frames.
In currently known embodiments, the half-frames are connected to one another by a pivot carried by the underframe; the pivot either comprises a shaft on which the ends of the underframe are threaded (French Patent 2.409.896) or comprises concentric rings of large diameter carried by the half-frames and cooperating with at least one ring carried by the underframe (French Patent 2.491.849).
In the case of a single shaft, this generally assures only rotational guidance; load-bearing is then effected by the lateral support.
Since the underframe is connected to the half-frame only by a central pivot, the central portion of the car lacks stability in motion.
To overcome this disadvantage and moreover to increase the length of each half-frame, an articulated vehicle is known (French Patent 2.086.846) of which the half-frames are on the one hand connected to one another by a spherical plain bearing and on the other hand are rotatably connected to the underframe, not about the same shaft as that of this spherical plain bearing but rather about one of the two separate pivots carried by the underframe in the longitudinal plane thereto and spaced apart equidistantly from the spherical plain bearing and the median transverse plane of the underframe.
Elastic elements naturally absorb the deflection in the arcs on which the half-frames can pivot with respect to the underframe.
This connection of the underframe by two pivots increases the stability of the car in motion, makes it possible to lower the floor of the car, and finally allows an increase in the useful length of the car by the value of the spacing between the two pivots.
To make profitable use of this latter advantage, known embodiments (French Patent 2.086.846) have located the pivots in proximity with the opposite ends of the underframe, and loading takes place on the lateral supports generally known as transoms, which both on the underframe and in embodiments have a single central pivot are disposed substantially in the same transverse plane as the pivot they supplement.
This type of embodiment has given excellent results for articulated vehicles with a single common axle, which are therefore reserved for light loads, but has led to excessive flexibility in the articulation of heavily loaded cars.
One object that the invention seeks to obtain is an articulated vehicle of the above type that is suitable for heavy loads.